In the past, where an in-vehicle audio-visual system is mounted, it has been necessary to connect the components by electric wires. Much labor has been required to mount them within a vehicle. Furthermore, by connecting electric wires, limitations are imposed on installation positions. This has made it difficult to create a free in-vehicle space.
On the other hand, it is conceivable that audio-visual devices are connected using wireless communication functions used in the field of personal computers and so on (see Patent Reference 1).
[Patent Reference 1] JP-A-10-32579
However, if the aforementioned wireless communication functions are used for in-vehicle communications, electromagnetic waves leak to the outside of the vehicle, producing the problem of eavesdropping.